The requested Chat looks very similar to Gantt chart (or at least same tool could be used). We previously describe in the forum how to make a simple Gantt chart with LightningChart(R) .NET. Please see https://forum.arction.com/viewtopic.php?f=23&t=1034
You can use Annotations (as in Forum’s project), PolygonSeries or LineCollections to build Gantt chart. The selection of object depends on the details you would like to render. For example, Annotations is most flexible object, which can have bitmaps, various fills, text styles etc. In contrast, LineCollections is the simplest form of bars/lines. However, more details you have - the higher are the rendering costs. Therefore, with several thousands of lines/objects you should use LineCollections.
You could check “Line Collections” example in our Demo App (XY -> Others) for illustration of idea. So basically each polygon should now be replaced with SegmentLine. Please note, more lines/segments you could combine to LineCollections – more efficient rendering will be. For example, you could combine all the lines/segments of single color (and same width) into one Collection.